This Blessed Plot — M.R.D. Meek

Lennox Kemp is hired by poor Mrs. Sorrento to follow her errant husband, and by the rich Courtenay twins, Vivian and Venetia, to oversee the legalities of their massive inheritance. But when the paths of these clients cross, Kemp discovers he's unwittingly become a bit player in an elaborately staged performance of greed, deceit, and murder.